Conventionally, it is proposed to detect an object existing in surroundings of a vehicle such as a preceding vehicle, a pedestrian or obstacles by using a distance measuring sensor such as an ultrasonic sensor mounted on the vehicle, and perform a various controls to improve a running safety of the vehicle such as actuating a braking device or notifying a driver based on an object detection result.
The distance measuring sensor has a detection range, and it transmits probe waves, and it is possible to receive a reflected wave reflected by an object within the detection range.
However, a position of the object existing around the vehicle may be outside the detecting range of the distance measuring sensor.
Further, even if the object exists within the detection range, a reflecting direction of the reflected wave changes depending on a shape of the object, and a case that it is impossible to detect the object may temporarily occur.
In this case, when it is assumed that the object does not exist in the surroundings of the vehicle, and the vehicle does not perform an actuation of the braking device, for example, there is a possibility that the vehicle may contact the object depending on the position of the object.
In this regard, there is an object detecting apparatus disclosed in the Japanese Patent Application Laid-Open Publication No. 2012-144157 for estimating the position of the object outside of the detection range of the distance measuring sensor.
In the object detecting apparatus disclosed in the Publication No. 2012-144157, when the position of the object is outside of the detection range of the distance measuring sensor, a distance between the vehicle and the object is estimated based on a previous object location detected by the distance measuring sensor and a distance moved by the vehicle as measured by a wheel speed sensor.
However, in the object detecting apparatus according to the Publication No. 2012-144157, a calculation accuracy of the distance between the vehicle and the object will be lowered when the distance moved by the vehicle is not accurately obtained after the position of the object is no longer detected by the distance measuring sensor.
For example, if the object is a moving object, it is not possible to estimate the distance between the vehicle and the object correctly even if the detection result of the wheel speed sensor is distance-converted.
In other words, it is not possible to accurately comprehend a relative position of the vehicle with respect to the object, and as a result, the calculation accuracy of the distance to the object is lowered.